Processing of biological and inorganic samples for the detection of mycobacteria is generally initially directed at clarification and removal of cellular or other debris, and reduction of contaminating microorganisms rather than at purification of mycobacteria per se. Thus, methods of processing biological and inorganic samples suspected of containing one or more mycobacteria, for the detection of such mycobacteria, are constrained by the presence of other, undesired microorganisms naturally present in such samples.
As one example, samples processed for mycobacterial analysis using "betaine-like" detergents as described in WO 95/27076 can still contain non-mycobacterial microorganisms in the sample at the completion of the processing. When attempts were made to culture the slow-growing mycobacteria from the processed samples, breakthrough growth of other faster-growing organisms present in the processed sample could overtake the culture, thereby causing a potential false positive result.
Such breakthrough growth is a problem as it can hinder or prevent the detection of slow-growing bacteria, and especially mycobacteria, in the sample. This problem is especially a concern for the culture of slow-growing pathogenic species of bacteria (like mycobacteria) as a patient can be misdiagnosed if the suspected microorganism cannot be cultured from that patient's samples. Hence a need exists for a method that promotes the selective recovery of a desired microorganism, especially a mycobacteria, from a s ample that may contain many other faster-growing microorganisms. Procedures designed to reduce the influence of contaminants on diagnostic utility would further improve the ability to correctly diagnose infections caused by bacteria containing mycolic acid structures, especially the diagnosis of mycobacterial infections. The invention described herein utilizes lytic enzymes as a means to purify bacteria containing mycolic acids structures for the purpose of reducing the influence of contaminants on diagnostic test results.
Noki, JP 05023167A describes a method for preparing sterile plant seedlings in which decontaminated seedlings were subjected to a vacuum. The seedlings were decontaminated by immersion into an enzyme solution that contained, inter alia, 0.1% glucanase for 2 hours at 30.degree. C. This is stated to result in the lysis of miscellaneous germ cell walls, and the removal of fungi that are attached to the plant body surfaces. However, such treatment was an attempt to sterilize the seedlings. Recovery of any viable microorganisms from the seedling cultures after the lytic enzyme treatment was clearly undesirable.